The present invention relates to a vehicle having a dual-branch exhaust-gas system.
Classic exhaust-gas systems run in the underfloor region of a passenger motor vehicle in a rearward direction from an internal combustion engine arranged in the vehicle front-end section, and normally open out into the surroundings via a tailpipe in a rear apron region.
German patent application DE 102 31 056 A1 of J. Eberspächer GmbH & Co. KG discloses a vehicle having a V-configuration engine with left-hand and right-hand cylinder banks. The two cylinder banks are assigned in each case one exhaust-gas manifold. Exhaust-gas outlets of the two exhaust-gas manifolds open into a pre-silencer. From the pre-silencer, a left-hand and a right-hand exhaust-gas tract lead into a rear-end region of the vehicle, where the exhaust gas emerges into the surroundings. The exhaust-gas tracts are of different design with regard to their damping action or their flow resistance, that is to say one exhaust-gas tract has a greater flow resistance than the other exhaust-gas tract.
The exhaust-gas system described in DE 102 31 056 A1 furthermore has an electronically actuable flap arrangement. It is provided that, in a lower rotational speed range of the internal combustion engine, the exhaust gas is conducted exclusively or predominantly through one of the two exhaust-gas tracts. In a medium rotational speed range, the exhaust gas is conducted exclusively or predominantly through the other of the two exhaust-gas tracts. And, in an upper rotational speed range, the exhaust gas is conducted in parallel through both exhaust-gas tracts.
Exhaust-gas systems which conduct the collective exhaust-gas stream via multiple exhaust-gas tracts to the vehicle rear end take up a relatively large structural space, because the individual components of the exhaust-gas tracts (pre- and post-silencers, etc.) must, for thermal reasons, be spaced apart sufficiently far from other components of the vehicle and/or correspondingly thermally insulated.
This applies, in particular, in the case of (highly) electrified vehicles, wherein it is sought to utilize the structural space in the central tunnel region for the integration of high-voltage battery components. The introduction of heat by the exhaust-gas system into adjacently arranged high-voltage battery components is particularly undesired, and under some circumstances constitutes an exclusion criterion for the arrangement of a high-voltage battery in the region of the central tunnel.
It is an object of the present invention to provide a vehicle having a multi-branch, in particular dual-branch, exhaust-gas system, which is suitable for vehicles in which restricted structural space conditions exist in the underfloor region (for example, in electrified vehicles or hybrid vehicles), wherein the exhaust-gas system should be acoustically as inconspicuous as possible at low levels of engine power, at low speeds or in standstill situations.
This and other objects are achieved by a vehicle, comprising: an internal combustion engine; and an exhaust-gas system which has at least one first exhaust-gas tract with at least one first exhaust-gas outlet opening into surroundings and at least one second exhaust-gas tract with at least one second exhaust-gas outlet opening into the surroundings, wherein as viewed in a direction of travel of the vehicle, the at least one second exhaust-gas outlet is located in front of the at least one first exhaust-gas outlet.
The starting point of the invention is a vehicle having an internal combustion engine (e.g. an Otto-cycle engine or a diesel engine) and an exhaust-gas system which has at least one first exhaust-gas tract with at least one first exhaust-gas outlet opening into the surroundings (atmosphere) and at least one second exhaust-gas tract with at least one second exhaust-gas outlet opening into the surroundings.
A core concept of the invention consists in that, as viewed in the direction of travel of the vehicle, the at least one second exhaust-gas outlet is situated in front of the at least one first exhaust-gas outlet. By contrast to DE 102 31 056 A1 as discussed above, it is thus specifically not the case that both exhaust-gas tracts extend rearward into the rear-end region of the vehicle.
It may rather be provided that, as viewed in a side view of the vehicle, the first exhaust-gas outlet is situated in a rear vehicle half (rear-end region of the vehicle) and the second exhaust-gas outlet is situated in a front vehicle half. It may, for example, be provided that the first exhaust-gas outlet is—similarly to the situation in most conventional vehicles—situated behind a rear axle of the vehicle.
By contrast, the second exhaust-gas outlet may be arranged in front of a bulkhead of the vehicle, that is to say in front of a passenger compartment of the vehicle. The internal combustion engine may also be arranged in this region, that is to say in front of the bulkhead of the vehicle, similarly to the situation in most conventional vehicles.
The second exhaust-gas outlet may be arranged in a side region of the vehicle front-end section, and may, for example, open laterally into the surroundings in front of the left-hand or the right-hand front wheel. In principle, it would however also be possible for the second exhaust-gas outlet to open laterally into the surroundings behind one of the two front wheels.
The first exhaust-gas tract has a first exhaust-gas pipe and the second exhaust-gas tract has a second exhaust-gas pipe (and in each case possibly further components, such as for example a catalytic converter, particle filter, etc.). It may be provided that the flow cross section or the “diameter” of the first exhaust-gas pipe is smaller than the flow cross section or the “diameter” of the second exhaust-gas pipe. Accordingly, less structural space is required for the first, “rearwardly leading exhaust-gas pipe” than for the second exhaust-gas pipe, which runs in the front of the vehicle.
Such an exhaust-gas system concept is suitable in particular for vehicles in which only relatively little structural space is available in the underfloor region, in particular in the region of a central tunnel of the vehicle body.
For example, it may be provided that the ratio between the flow cross section of the first exhaust-gas pipe and the flow cross section of the second exhaust-gas pipe lies in a range between 5% and 50%, in particular in a range between 10% and 20%. The flow cross section of the first exhaust-gas pipe is thus significantly smaller than the flow cross section of the second exhaust-gas pipe, and accordingly takes up less structural space.
The internal combustion engine of the vehicle has at least one exhaust-gas manifold which combines the exhaust gas from individual cylinders of the internal combustion engine to form a collective exhaust-gas stream at an exhaust-gas manifold outlet.
An exhaust-gas system according to the present invention furthermore has an “exhaust-gas branching point device” (“exhaust-gas branching point” for short). The exhaust-gas branching point in turn has an exhaust-gas inlet for the collective exhaust-gas stream passing from the internal combustion engine or from the at least one exhaust-gas manifold of the internal combustion engine, and also a first exhaust-gas outlet, to which first exhaust-gas tract is connected, and a second exhaust-gas outlet, to which the second exhaust-gas tract is connected.
A catalytic converter and/or a particle filter (Otto-cycle engine particle filter or diesel particle filter depending on the type of internal combustion engine) may be arranged in a region between the exhaust-gas manifold outlet of the at least one exhaust-gas manifold and the exhaust-gas inlet of the exhaust-gas branching point. It may for example be provided that the particle filter is arranged downstream of the catalytic converter in the flow direction of the exhaust gas.
In a first variant of the invention, a “central pre-silencer” is provided, which may likewise be arranged in the exhaust-gas system section between the internal combustion engine and the exhaust-gas inlet of the exhaust-gas branching point. The exhaust gas passing from the internal combustion engine thus flows in an already sound-deadened manner into the exhaust-gas branching point.
It may alternatively be provided that the exhaust gas passing from the internal combustion engine flows in a substantially non-sound-deadened manner into the exhaust-gas branching point, that is to say that no central pre-silencer is arranged in the exhaust-gas system section situated between the internal combustion engine and the exhaust-gas branching point, but rather a first and second pre-silencer are arranged in the first exhaust-gas tract and in the second exhaust-gas tract.
In both variants, it is furthermore possible for, in each case, one first and second end silencer to be arranged in the first exhaust-gas tract and in the second exhaust-gas tract.
It is preferably possible for the second and/or the first exhaust-gas tract to be selectively activated or deactivated. For this purpose, a switching device may be provided which can assume three different operating states. Accordingly, in a manner dependent on the presently set operating state of the switching device, the entire exhaust-gas stream passing from the internal combustion engine (collective exhaust-gas stream) is selectively either:
(1) conducted exclusively via the first, “rear” exhaust-gas tract into the surroundings (1st operating state), or
(2) exclusively via the second, “front” exhaust-gas tract (2nd operating state), or
(3) “split”, that is to say a first partial exhaust-gas stream of the collective exhaust-gas stream is conducted via the first exhaust-gas tract and the remaining (second) partial exhaust-gas stream of the collective exhaust-gas stream is conducted via the second exhaust-gas tract into the surroundings (3rd operating state).
During operation of the vehicle, it may be provided that, at low levels of power of the internal combustion engine and in the presence of the associated relatively small exhaust-gas mass streams, the exhaust gas is conducted primarily or exclusively rearward via the first exhaust-gas tract, and emerges into the surroundings in the region of the vehicle rear-end section. This has the advantage that, in the presence of low load, that is to say when at a standstill and/or at low speeds, the exhaust-gas stream is discharged rearward into the atmosphere, and it is in no way possible for said exhaust-gas stream to enter the passenger compartment via a possibly open side window of the vehicle or via the air-conditioning system intake.
At high levels of power of the internal combustion engine and in the presence of the associated relatively large exhaust-gas mass streams, the exhaust gas may be conducted into the surroundings primarily or exclusively via the second exhaust-gas tract in the region of the vehicle front-end section. It may thus be provided that, at high levels of power or at high speeds of the vehicle, the second exhaust-gas tract is “activated”, or that, at high levels of power, a “switchover” to the second exhaust-gas tract is performed. Owing to the flow conditions at relatively high vehicle speeds, a situation is ruled out in which exhaust gas can pass into the passenger compartment through a possibly open side window of the vehicle or via the air-conditioning system intake.
As an alternative to the first variant mentioned above, a switching device may be provided which can assume only two different operating states, wherein, in a manner dependent on the set operating state, the collective exhaust-gas stream:
(1) is either conducted via the first exhaust-gas tract into the surroundings (1st operating state), or
(2) a first partial exhaust-gas stream is conducted via the first exhaust-gas tract into the surroundings and a second partial exhaust-gas stream is conducted via the second exhaust-gas tract into the surroundings (2nd operating state).
By contrast to the first variant, it is thus always the case in the second variant that at least a partial volume stream of the collective exhaust-gas stream is conducted via the first exhaust-gas tract into the surroundings.
The dual-branch exhaust-gas system according to the invention is used in particular for “electrified vehicles”. Owing to the relatively short structural length of the second, front exhaust-gas tract, this may duly be acoustically somewhat more strongly perceptible than the first, rear exhaust-gas tract. However, through corresponding actuation of the switching device, it can be achieved that, in situations in which the noises generated by the exhaust-gas system should be as low as possible (for example in standstill situations of the vehicle or at low speeds), the exhaust gas is conducted primarily or exclusively rearward in the direction of the rear end of the vehicle, and into the surroundings, via the acoustically considerably less perceptible first exhaust-gas tract. In this way, it is possible, in particular in the case of hybrid vehicles, for the acoustic perceptibility of the exhaust-gas system to be limited to a minimum, whereby the vehicle can be experienced by the driver as an “electrified vehicle” to a particularly high degree.
For this purpose, the switching device has at least one switching element, which may be formed for example by an electrically actuable flap. The at least one switching element may be arranged for example in or at the exhaust-gas branching point and may be formed for example as a switchover flap, which is adjustable in stepped or continuously variable fashion. A “switchover flap” is to be understood to mean a switching device, by means of the actuation of which the flow cross section of one exhaust-gas tract is increased in size and at the same time the flow cross section of the other exhaust-gas tract is decreased in size.
Alternatively or additionally, the switching device may have in each case one switching element in each of the two exhaust-gas tracts, wherein the two switching elements are controllable or actuatable independently of one another. Such switching elements integrated into the partial tracts may be formed for example as sliding flaps with the capability of continuously variable adjustment.
For the control of the switching device, control electronics are provided which switch the switching device into a particular operating state:
(a) in a manner dependent on the operating state of the internal combustion engine (for example in a manner dependent on the present engine power, the engine rotational speed or the like), and/or
(b) in a manner dependent on the operating state of the vehicle (for example in a manner dependent on the speed of the vehicle and/or on the present position of the vehicle (within built-up areas/outside built-up areas, etc.) and/or in a manner dependent on a noise level measured by a noise sensor in the passenger cell of the vehicle or on the body of the vehicle).
In particular, it may be provided that the switching device is situated in an operating state in which the collective exhaust-gas stream is conducted entirely or predominantly (for example more than 50%, 60%, 70%, 80%, 90%) “rearward” via the first exhaust-gas tract into the surroundings if the power output by the internal combustion engine and/or the speed of the vehicle is in a predefined low power range or in a predefined low speed range (for example V<60 km/h).
As already mentioned, the exhaust-gas system according to the invention is suitable in particular for hybrid vehicles, in which an electric drive machine provided for generating vehicle propulsion is arranged in the region of the rear axle. In such hybrid vehicle concepts, there is generally only little structural space, in which a large-volume exhaust-gas system could be arranged, available in the underfloor region of the vehicle. The exhaust-gas system according to the invention, in which the exhaust-gas pipe leading “rearward” is of relatively small dimensions, is therefore particularly suitable for such vehicle concepts.
The invention may self-evidently also be used in other vehicle concepts. These include for example a vehicle concept in which a so-called “range extender” (“small” internal combustion engine which drives a generator provided for generating electricity) is arranged together with an electric machine in the front-end region of the vehicle, wherein a (large) electrical energy store is arranged in the underfloor region of the vehicle, that is to say below the passenger cell.
In one refinement of the invention, it is provided that the first exhaust-gas tract or at least a partial section of the first exhaust-gas tract is arranged in a central longitudinal region situated below a passenger compartment of the vehicle. In most vehicles, this central longitudinal region is formed as a so-called “central tunnel”. An arrangement of the first exhaust-gas tract or of a partial section thereof in a central longitudinal region of the underfloor space of the vehicle is, however, not imperatively necessary.
The first exhaust-gas tract or a partial section of the first exhaust-gas tract may also—in relation to a central longitudinal axis of the vehicle extending in a vehicle longitudinal direction—be arranged eccentrically or in a laterally offset manner. For example, the first exhaust-gas tract or a partial section of the first exhaust-gas tract may be arranged laterally adjacent to one of the two sills (body region which extends in the vehicle longitudinal direction below the doors of the vehicle), wherein the sill conceals or covers the first exhaust-gas tract or a partial section of the first exhaust-gas tract from the outside. If the sills are formed as hollow profiles, the first exhaust-gas tract or a partial section of the first exhaust-gas tract may also be arranged within the sill profile.
If the vehicle is an electrified vehicle or a hybrid vehicle, it may be provided that electrical energy store units are arranged in a region to the left and in a region to the right of the partial section of the first exhaust-gas tract or of the central tunnel below the passenger compartment. Since the flow cross section of the first exhaust-gas tract is relatively small, the thermal loading of high-voltage components possibly arranged in said region is also correspondingly low. As an alternative to this, as already mentioned above, it is also possible, in the case of a hybrid vehicle in which an electrical energy store is arranged in the central region of the underfloor region, for the first exhaust-gas tract or a partial section of the first exhaust-gas tract to be arranged laterally adjacent to the electrical energy store, in particular in a region between the electrical energy store housing and the left-hand or right-hand sill.
With regard to the vertical alignment of the first exhaust-gas tract or of a partial section of the first exhaust-gas tract, there are likewise numerous possibilities.
The first exhaust-gas tract or a partial section of the first exhaust-gas tract may for example be arranged in the (vertical) region in which the electrical energy store is also arranged. In the case of a central arrangement of the first exhaust-gas tract or of a partial section of the first exhaust-gas tract, it may be provided that the first exhaust-gas tract or a partial section of the first exhaust-gas tract extends between two energy store parts (right-hand part and left-hand part) in the direction of the vehicle rear end.
As an alternative to this, it would also be possible for the first exhaust-gas tract or a partial section of the first exhaust-gas tract to be arranged above or below the electrical energy store, which has the advantage that the energy store can be designed without problems as a single-part, for example cuboidal housing.
In the above description, where the expression “at least” is omitted in conjunction with the first exhaust-gas tract, the first exhaust-gas outlet, the second exhaust-gas tract and/or the second exhaust-gas outlet, this is not to be understood in a restrictive sense, but is rather to be understood as meaning also that more than one first exhaust-gas tract, first exhaust-gas outlet, second exhaust-gas tract and/or second exhaust-gas outlet may be provided.
The wording “exhaust-gas system with at least one first exhaust-gas tract” or “at least one first exhaust-gas outlet that opens into the surroundings” used above is thus to be understood to mean that, in all exemplary embodiments of the invention, it is in principle also possible for exhaust gas to be conducted into the surroundings via two or via more than two “first exhaust tracts” or “first exhaust-gas outlets”. Correspondingly to the abovementioned core concept of the invention, the second exhaust-gas outlet would then be situated in front of the two first exhaust-gas outlets or in front of the more than two first exhaust-gas outlets. Analogously, it is also possible for two or more than two second exhaust-gas tracts and/or two or more than two second exhaust-gas outlets to be provided. The invention is thus expressly not restricted to exactly one first exhaust-gas outlet and exactly one second exhaust-gas outlet.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.